Backing off mechanism for grinding machines



Dec. 8, 1931. H. M.- ALLISON 1, 7

- BACKING-OFF MECHANISM FOR GRINDING MACHINES Filed March 27, 1951 4 Sheets-Sheet 1 mumw' Dec. 8, 1931. H. M. ALLISON BACKING-OFF MECHANISM FOR GRINDING MACHINES 4 Sheets-Sheet 2 Filed March 27, 1951 'Dec. 8, 1931. H. M. ALLISON 1,835,687

BACKING-OFF MECHANISM FOR GRINDING MACHINES Filed March 27, 1931 4 Sheets-Sheet 3 1 J m s ,W M N m4 W 7 w Q ,1! H mm @MW 3% QM I QM \m V V W &N 6 \N .N. N Nw \w S Q 3 M D 1931- H. M. ALLISON 8 BACKING-OFF MECHANISM FOR GRINDING MACHINES Filed March 27, 1931 4 Sheets-Sheet 4 Q Ede-12W Q8 flay W. 466019071. d qstfi M 5 tap toprovide a desired clearance.

Patented Dec. 8, 1931 uNrrs STATES I HARVEY 1V1. ALLISON, OF

PATENT emu V WORCESTER, MAssLc'nI-Isn'rm's, nss'IG Non To ironN BATH, o'ii WORCESTER, MessAoHUsE ris' IBA'GKING'OFE Mn'onnNIsM Eon. GRINDING MACHINES Application filed March 27, 1931-. Serial No. 52597-89.

This invention relates to mechanism for use in a machine for grinding taps or similar articles, and. provides mechanism for efiectively backing H or relieving the teeth of a Mechanism for this general purpose is shown in the prior application of Allison and Walker, Serial No. 381,568,1iled July 27, 1929.

It is the general object of my present inven- 1 tion to improve and simplify the mechanism shown in said prior application, making the same more convenient and economical to construct, more easy to adjust with respect to the work, and less exposed to the action of particles of abrasive.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appendedclaims.

A preferred form of the invention is shown in the drawings, in which Fig. l is a plan view of certain parts of my improved mechanism; v

2 is a detail side elevation, looking in the direction of'the arrow 2in Fig. 1;

' Fig. 3 is a diagrammatic plan view, showing the relation of the wheel and work; Fig. 4 is an end elevation, looking in the direction of the arrowt in Fig.1; 2

Fig. 5 is a rear elevation, partly in section, and looking in the direction of the arrow 5in Fig. 1;

Fig. 6 is a plan View of certain parts shown in Fig.5; 7

Fig. 7 is a detail sideelevatlon, looking in the direct-ionoi" the arrow 7 in Fig. 6;

Fig. 8 is a sectional plan view of adriving "connection, taken along the line ,8-8 in Fig. 4;

. h Fig. 9 is'a sectional plan View of certain eccentric driving mechanism; T

Fig. 10 is a plan view of portions oithe.

eccentric driving sha-ft;

Fig.1:1 is a plan view of an eccentric member' g I Fig 5.12 is a side elevation thereof, looking in the direction of the arrow 12 in Fig. 11

Fig. 13 is -a ,plan view of aloe-king collar,

and e e V ed on awheel slide 26.

The wheelhead 24 is adjustable forward rear of the wheeljslide:

14' is a diagrammat-i'c 'side elevation,

showing the method of setting the work.

Referring to Figs. 1 and l, I have-shown portions of agrindlng machine baseor frain'e 20,1 ha'ving longitudinally extending guide- Ways for a work table 21 and a wheel table 22. A grinding wheel G (Fig. 1) is mounted in'=a wheel head 24 (Fig. 5) which is supportand rearward on the wheel slide 26,such adjustment being accomplished by an adjusting screw 27 1nounted in thehead '2-fLa-nd threaded in a nut- 28 secured in abracket 29 (Fig. 5.)

mounted on the slide '26. The screw 27 may be turned manually or automatically for adjustment of the wheel toward or away from the work. o I

The work W (Fig. may be'supported on a work spindle 30 and tail center 31,secured respectively ina head stock -82 and a tail stock (not shown) carried by the work table-21.

During the operation of the machine, the

work table 21 is reciprocatedby means of a lead screw 33 (Fig.4) and the spindle 30ris'" rotated through suitable connections to a driving shaft :35 (Fig. 1).

I The wheel table 22 may be adjusted longi- 'tudina lly on its guideways by an adjusting screw '37. This ustment of the wheel table is commonly used for shifting the wheel to different longitudinal sections of the work and for adjusting the machine to pieces 'of work of widely 'diiierent lengths. The table 22 commonly remains fixed ingpositionon the base 2O during the'operation of the machine.

I will now describe the-mechanism forgiving the wheel slide 26 a forward and rearward reciprocating movement for relieving the teeth of a tap OY'Ot-llBI :piece of work.

The wheel slide 26 (Fig. 5) is supported onanti-frictionbearings 40 for-easy forward and rearward slidingmovement on the wheel tablel22. A rock shaft 42 is :pivotally mountward from the wheel table 22 (Fig; '2). An

rock shaft 42 and isslotted to a'eceivea crossrod 46 mounted in brackets 17 and47 at the link 51 (Figs. 1 and 2) which extends forward.

7 bearing arms 43 and 44.

A secondarm 50 projects upward from the rockshaft 42 and is pivotally connected to a over the Wheel table 2-2 and is provided atits forward end with a 'bushing521 (Fig. 9) for an eccentric member 53 which is rotatable therein. v

The member 53 has a circular opening 54 (Fig. 12) which fits closely on an eccentric portion 55 (Figs. 9 and 10) of an'eccentric shaft56 which is rotatably mounted in bearings 57 and '58 formed on a bracket 59 (Fig.

4) securedt'o the top of the wheeltable 22.

The eccentric member 53 is provided with a flange ,60 having notches 61 -to which a wrench or. spanner may be applied for adjusting the eccentric member.

One outer end of the hub of the eccentric member 53 is serrated as indicated at 62 (Fig. 11'), and a collar 63is provided with teeth 64 corresponding to the serrations on the eccentric member; The collar 63 is keyed to the eccentric portion '55- of the shaft 56 and is forced against the ec'centric member 53 by a lock nut 66. At its opposite end, the eccentric member 53 abuts against acollar 67 interposed between the eccentric member 53 and an enlarged bearing portion 68 of the eccentric shaft 56. The outer end of the shaft 56 is still further enlarged'to provide a cylindrical portion 69 of the eccentric shaft 56 and is rotatable there- I -with. The collar'71 is provided with numbered graduations for a purpose to be described and the collar-63 is similarlygraduated."

The driving head 7 O is slotted to receive a square shaft 74 and is also recessed to receive the cylindrical endportion 7 5 thereof.

The shaft 74 may be secured in the'head 70 by insertinga cross pin 7 6 (Fig. 9).

' The shaft 74 extends through a square axial openingin a sleeve 77 (Fig. 8) rotatable in bearings 78 and 79 formed in a bracket 80 (Figs. 1 and 4) extending rearwardfrom a gear plate 81 mounted'on and secured to the head stock 32' (Fig. 1) of the grinding machine. I v V The middle portion of the sleeve 77 (Fig. 8) is formed as a pinion 84 which is connected by change gears 85, 86, 87 and 88 (Figs. l-and 4) to a gear 90 on a driving shaft 91. The

shaft 91 is also connected through gears 92 and 93 tothe lead screw 33 and by additional gears (not-shown) to' the work spindle 30 T (Fig. 3). The eccentric member 53 is thus rotated in a definitespeed'relation' to the work spindle 30 and to the lead screw i r By using different arrangements of change gears, the-eccentric 'member53 may be "is tated to advance and withdraw the grinding wheel any desired number of times during each revolution of the tap or other work on the work table. For instance, for the four flute tap shown in Fig. 14 the grinding wheel G will be advanced and withdrawn four times for each revolution of the work.

The square shaft 74 provides a constant of the lands of the work W and to engage the .upper or cutting edge of the rearmost land.

Thisgauge bar 95 is used in setting up the machine and the method of using the same is as follows: 7

The collar '63 (Fig. 13) is graduated toindicate thousandths of an inch in forward and rearward movement of the. wheel carriage andgrinding wheel. As previously stated, this collar is keyed to the'eccentric portion 55 of the eccentric driving shaft56. To. set the machine, the lock nut 66 is backed off, allowing the serratedcollar 63 to clear theteeth on the end of the. eccentric member 53. The eccentric member 53 is then turned by a wrench or spanner until a zero or index line on the eccentric member 53 corresponds. with the index line numbered 5 on the collar 63. tightened to lock the parts together in their adjusted relation.- When thus locked, the" eccentric member 53 will be in such relation to the eccentric portion 55 of the driving shaft 56 that the throw of the eccentric member will correspond to a relieving movement of five thousandths of an inch for the grinding wheel G. i

It is now necessary to angularly adjust the work with relation tothe forward and rearward movement of the grinding wheel, so that the grinding wheel may be at its rearmost position as the cutting edge of each land of the tap arrives in grinding position.

Toaccomplish this result,.the gauge 95 (Figs. 4 and 14) is swung into position and the work W-Yis turned onthe work centers until the cutting'edge of one of the lands engages the shoulder 98 of the gauge, as shownin Fig. 14. r

The driving mechanism of the machine is then turned manually until'the division 5 on angular relation that when the eccentricity The collar 66 is then is set for five thousandths on the collar 63 and the collar 71 is set to bring the graduation 5 opposite the index 100, the grinding wheel G will be in its rearmost position. The driving dog or chuck is then adjusted to retain the work IV in the desired fixed relation to the work spindle 30. The machine is then ready to proceed with the grinding and relieving of the tap.

The setting does not ordinarily need to be repeated until another and different lot of taps are to be relieved.

The eccentric member 53 acts to move the grinding wheel positively both toward and away from the work but in orderto eliminate any back-lash, a spring 102 (Fig. 7) is mounted between the wheel table 22 and an arm 103 supported by rods 104 extending rearward from the wheel slide support 26. The spring 102 takes up all back-lash which might otherwise develop and prevents the possibility of chatter marks.

The mounting of the rock shaft 42 at the rear of the machine is of substantial advantage over the construction shown in the previous Alison and Walker application, as the parts are much more easily accessible for inspection or ad ustment and are also substantially removed from the work and the grinding wheel and are more easily protected from the action of abrasive'particles.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is 1. In a grinding machine, a grinding wheel, a wheel head, a wheel slide, a wheel slide support, a rock shaft mounted in bearings at the rear of said support and directly connected to the rear of said wheel slide, an arm on said rock shaft, an eccentric member mounted on said support and rotatable in timed relation to the rotation of the work, and a link extending forward from said arm and above said wheel slide support and having a bearing portion fitting said eccentric member.

2. In a grinding machine, a grinding wheel, a wheel head, a wheel slide, awheel slide sup-. port, a rock shaft mounted in bearings: at the rear of said support and having an arm slotted to engage a cross rod mounted in brackets at the rear of said wheel slide, a second arm on said rock shaft, an eccentric member mounted on said support and rotatable in timed relation to the rotation of the work, and a link extending forward from said arm and above said wheel slide support and having a bearing portion fitting said eccentric member.

3. In a grinding machine, a grinding wheel slide, a support therefor, means to reciprocate said slide forward and rearward between predetermined limits on said support, said reciprocating means including a shaft mounted on said support andhaving an eccentric portion.

and an eccentric member mountedthereoma other, an index on said eccentric member for one collar, and an index on said support for the other collar, said graduations and indioes cooperating to show the range of movement of the grinding wheel and the rearmost position thereof.

4. In a grinding machine, a grinding wheel slide, a support therefor, means to reciprocate said slide forward and rearward between predetermined limits'on said support, said reciprocating means including a shaft mounted on said support and having an eccentric portion and an eccentric member mounted thereon, a pair of graduated collars mounted on said shaft, both of which collars being fixed angularly with respect to said shaft and to each other, an index on said eccentric member for one collar, an index on said support for the other collar, and a gauge bar for setting the work in an angular position corresponding to the rearmost position of the grinding wheel as determined by said graduations and indices.

5. In a grinding machine, a grindingwheel a wheel slide, an eccentric driving shaft, an eccentric member angularly adjustable on said shaft to vary the combined eccentric effect, connections between said eccentric memberand said wheel slide, and means to indicate the position of said eccentric member which corresponds to rearmost position of said wheel slide.

6. In a grinding machine, a grinding wheel, a wheel slide, an eccentric driving shaft, an eccentric member angularly adjustable on said shaft to vary the combined eccentric effect, connections between said eccentric memher and said wheel slide, means to indicate the position of said eccentric member which corresponds to rearmostposition of said wheel slide, and means to set the work in a definite less angular position corresponding to said rearward position.

In testimonywhereof have hereunto affixed my signature.

I HARVEY M. ALLISON. 

